Question

In the WebSphere Application Server admin console, there is a section under
Application servers > server1 > Process definition > Environment Entries

I don’t understand what environment entries are. They are not system properties because they are defined in Process definition > Java Virtual Machine > Custom properties.

So what’s that? How can they be accessed from within an application.

Answer 1

Quoting http://www-01.ibm.com/support/docview.wss?uid=swg21254153 , official description is;

Environment entries can be used to specify variables not specific to
WebSphere Application Server, but are defined by other elements, such
as UNIX®, Language Environment® (LE), or third-party vendors, among
others. These variables tend to be operating system-specific.

So they are OS specific (i.e PATH for Windows, LIBPATH for AIX, LD_LIBRARY_PATH for Solaris).

For an example case where usage is necessary; quoting http://publib.boulder.ibm.com/infocenter/dmndhelp/v7r0mx/topic/com.ibm.wbit.help.runtime.doc/deploy/topics/rcfglibadapters.html

If a native library is dependent on other native libraries, the
dependent libraries must be configured on the LIBPATH of the JVM
hosting the application server (rather than on the native path shown
in the above figure) in order for that library to load successfully.
You should configure an environment entry by selecting Servers >
Application Servers > server_name > Java and Process Management >
Process Definition > Environment Entries (where server_name is the
name of the server; for example, server1). On the Environment Entries
page, create a new environment entry to specify the LIBPATH of the
JVM.

You can access these variables by using System.getenv() (not System.getProperties(), which returns custom properties and generic JVM arguments).